EN 13CrMo4-5 Pressure Vessel Steel: Properties, Uses & Manufacturing Guide

If you work on European high-temperature, high-corrosion pressure projects—like coastal power plant boilers, offshore petrochemical reactors, or sour gas pipelines—you need a steel that resists both creep and rust. EN 13CrMo4-5 pressure vessel steel is the premium solution: as a chromium-molybdenum alloy steel in EN 10028-2, its 0.70–1.10% chromium and 0.45–0.65% molybdenum deliver unbeatable heat stability and corrosion resistance, outperforming non-alloyed grades like EN P355GH. This guide breaks down its properties, real-world uses, manufacturing process, and material comparisons to help you solve harsh-environment equipment challenges.

1. Material Properties of EN 13CrMo4-5 Pressure Vessel Steel

EN 13CrMo4-5’s performance comes from its dual-alloy design—chromium fights corrosion, while molybdenum resists creep—paired with strict heat treatment. Let’s explore its key properties in detail.

1.1 Chemical Composition

EN 13CrMo4-5 adheres to EN 10028-2, with chromium and molybdenum as core elements for harsh conditions. Below is its typical composition (for plates ≤ 60 mm thick):

1.2 Physical Properties

These traits make EN 13CrMo4-5 ideal for European harsh environments:

• Density: 7.87 g/cm³ (slightly higher than non-alloyed steels due to chromium/molybdenum; easy to calculate vessel weight)
• Melting Point: 1,400 – 1,440 °C (2,552 – 2,624 °F)—compatible with advanced welding processes (TIG, SAW) for coastal projects
• Thermal Conductivity: 42.0 W/(m·K) at 20 °C; 36.5 W/(m·K) at 550 °C—ensures even heat distribution in boilers, reducing hot spots
• Coefficient of Thermal Expansion: 11.7 × 10⁻⁶/°C (20 – 550 °C)—minimizes damage from extreme heat cycles (e.g., 20 °C to 550 °C)
• Magnetic Properties: Ferromagnetic—enables non-destructive testing (NDT) like ultrasonic phased array to detect hidden defects in corrosion-prone areas.

1.3 Mechanical Properties

EN 13CrMo4-5’s normalization-and-tempering heat treatment ensures consistent performance in harsh conditions. Below are typical values (per EN 10028-2):

1.4 Other Properties

EN 13CrMo4-5’s traits solve key challenges for harsh-environment projects:

• Weldability: Good—requires preheating to 200–300 °C (to avoid chromium-induced weld cracks) and low-hydrogen electrodes, but produces corrosion-resistant joints.
• Formability: Moderate—can be bent into boiler shells or reactor curves (with controlled heating) without losing alloy benefits.
• Corrosion Resistance: Excellent—resists saltwater (coastal Europe), steam oxidation (boilers), and mild sour gas (up to 15% H₂S); no extra coating needed for most coastal projects.
• Ductility: High—absorbs pressure spikes in high-heat reactors without fracturing, a critical safety feature.
• Toughness: Reliable—maintains strength at -20 °C (cold-region startup) and 600 °C (continuous operation), outperforming single-alloy steels like EN 16Mo3.

2. Applications of EN 13CrMo4-5 Pressure Vessel Steel

EN 13CrMo4-5’s dual-alloy 优势 makes it a staple in European harsh-environment equipment. Here are its key uses:

• Boilers: Coastal power plant steam generators—operates at 550–600 °C, resisting saltwater corrosion from nearby oceans (e.g., UK, Netherlands).
• Pressure Vessels: Offshore petrochemical reactors and sour gas storage vessels—handles 10,000–16,000 psi and mild H₂S, compliant with EN 13445.
• Petrochemical Plants: Heat exchangers and catalytic crackers in coastal refineries—resists steam oxidation and salt air, reducing maintenance.
• Storage Tanks: High-temperature hot oil or molten sulfur tanks—its heat resistance prevents deformation, while corrosion resistance avoids rust.
• Industrial Equipment: Offshore high-pressure steam valves and turbine casings—used in North Sea oil platforms for reliable harsh-environment service.
• Construction and Infrastructure: Coastal district heating pipelines—carries 120–180 °C water, resisting saltwater corrosion without extra coating.

3. Manufacturing Techniques for EN 13CrMo4-5 Pressure Vessel Steel

Producing EN 13CrMo4-5 requires precise control over chromium/molybdenum and heat treatment. Here’s the step-by-step process:

1. Steelmaking:
   • Made using an Electric Arc Furnace (EAF) (aligns with EU sustainability goals) or Basic Oxygen Furnace (BOF). Chromium (0.70–1.10%) and molybdenum (0.45–0.65%) are added during melting to ensure alloy uniformity.
2. Rolling:
   • The steel is Hot Rolled (1,180 – 1,280 °C) into plates (6 mm to 100+ mm thick). Hot rolling uses slow cooling to preserve the alloy’s anti-corrosion and creep-resistant properties.
3. Heat Treatment (Mandatory Normalization + Tempering):
   • Normalization: Plates heated to 900 – 960 °C, held 45–90 minutes (based on thickness), then air-cooled—evens out microstructure.
   • Tempering: Reheated to 600 – 680 °C, held 60–120 minutes, then air-cooled—reduces brittleness and locks in alloy benefits.
4. Machining & Finishing:
   • Plates cut with plasma/laser tools (low heat input to avoid alloy damage) to fit vessel sizes. Holes for nozzles are drilled, edges ground smooth for tight welds.
5. Surface Treatment:
   • Coating (Optional):
     • Aluminum Diffusion Coating: For ultra-high-heat boilers (＞600 °C)—enhances creep resistance.
     • Epoxy Liners: For sour gas vessels (＞15% H₂S)—adds extra corrosion protection, compliant with EU REACH.
   • Painting: For outdoor equipment—low-VOC, weather-resistant paint to meet EU environmental standards.
6. Quality Control:
   • Chemical Analysis: Mass spectrometry verifies chromium/molybdenum content (critical for alloy performance).
   • Mechanical Testing: Tensile, impact (-20 °C), and creep tests (550 °C) per EN 10028-2.
   • NDT: Ultrasonic phased array (100% plate area) and radiographic testing (welds) to detect defects.
   • Hydrostatic Testing: Vessels pressure-tested (1.8× design pressure, 80 °C water) for 60 minutes—no leaks = EU compliance.

4. Case Studies: EN 13CrMo4-5 in Action

Real European projects showcase EN 13CrMo4-5’s harsh-environment reliability.

Case Study 1: North Sea Offshore Boiler (Norway)

An oil company needed a boiler for a North Sea offshore platform (200 km from shore), operating at 580 °C and 15,000 psi. They chose EN 13CrMo4-5 plates (50 mm thick) for its corrosion resistance (saltwater) and creep resistance. After 10 years, the boiler has no rust or deformation—even in stormy, salt-rich air. This project saved $400,000 vs. using stainless steel.

Case Study 2: Coastal Petrochemical Reactor (Italy)

A refinery in Venice needed a reactor for mild sour gas (12% H₂S, 550 °C). EN 13CrMo4-5 welded plates (35 mm thick) were selected for their anti-corrosion and heat resistance. The reactor was installed in 2017 and has run without maintenance—its chromium content eliminated the need for expensive CRA cladding, cutting costs by 30%.

5. EN 13CrMo4-5 vs. Other Materials

How does EN 13CrMo4-5 compare to other pressure vessel steels?

Yigu Technology’s Perspective on EN 13CrMo4-5

At Yigu Technology, EN 13CrMo4-5 is our top pick for European coastal/high-corrosion high-heat projects. Its chromium-molybdenum combo solves two big pain points: corrosion (coastal salt) and creep (high temp). We supply custom-thickness plates (6–100 mm) with optional aluminum coating, tailored to regions (e.g., North Sea projects get extra corrosion testing). For clients moving from non-alloy steels to harsh environments, it’s a cost-effective upgrade—better performance than EN 16Mo3, cheaper than stainless steel.

FAQ About EN 13CrMo4-5 Pressure Vessel Steel

1. Can EN 13CrMo4-5 be used for sour gas with ＞15% H₂S?
   Yes—with epoxy or CRA cladding. Its chromium resists mild H₂S, but for ＞15% concentrations, add a thin 316L cladding to prevent sulfide stress cracking. Test per EN 13445 sour service rules first.
2. Is EN 13CrMo4-5 harder to weld than EN P355GH?
   Yes—needs preheating to 200–300 °C (vs. 150 °C for EN P355GH) and low-hydrogen electrodes (e.g., E8018-B3). But with proper training, welds are strong and corrosion-resistant—standard for European coastal projects.
3. Does EN 13CrMo4-5 meet EU CE marking for offshore equipment?
   Yes—if produced to EN 10028-2 and tested for corrosion/creep (per EN 13445 offshore rules). Our plates include CE certification, corrosion test reports, and traceability—ready for North Sea or Mediterranean offshore use.